Optimization of Culture Conditions for High Cell-Density Fermentation of Bovine Escherichia coli

文献类型： 外文期刊

第一作者： Liu, Jishan

作者： Liu, Jishan;Li, Shuguang;Fu, Qiang;Xiao, Yueqiang;Qu, Guanggang;Shen, Zhiqiang;Cheng, Likun;Liu, Jishan;Li, Shuguang;Shen, Zhiqiang;Cheng, Likun;Xia, Xiaojing;Hu, Hongmei

作者机构：

关键词： Escherichia coli; Acetate; Dissolved oxygen; Feeding strategy; Metabolic flux distribution

期刊名称：KAFKAS UNIVERSITESI VETERINER FAKULTESI DERGISI （ 影响因子：0.685； 五年影响因子：0.655 ）

ISSN： 1300-6045

年卷期： 2018 年 24 卷 5 期

页码：

收录情况： SCI

摘要： Bovine Escherichia coli infection, which causes major economic losses to the cattle industry each year, can be prevented by administering formalin-inactivated vaccine. However, to enhance the application of this vaccine, the cell density of the formalin-inactivated E. coli should be boosted. This can be achieved by reducing the accumulation of acetate, a primary inhibitory metabolite in E. coil fermentation. To this end, the present study investigated the effect of pH, dissolved oxygen (DO) levels, and feeding methods on bovine E. coil fermentation, and developed two-stage pH and DO control strategies and a combined pH- and DO-mediated feeding strategy for the fermentation. The optimized conditions for Bovine E. coil were pH 7.0 at 0-10 h, 6.5 at 10-24 h; DO 50% at 0-10 h, 30% at 10-24 h; pH and DO feedback feeding at 0-10 h and 10-24 h, respectively. With Bovine E. coli fermentation under the optimized conditions, the acetate accumulation was 1.12 g/L and the cell density was 36.47 (OD600), which were 59.12% lower and 77.29% higher than these with the original conditions (pH 7.0; DO 20%; residual glucose concentration maintained at 2.0 g/L). After analyzing the main nodes of acetate synthesis, it was found that the lower carbon flux enters the Embden-Meyerhof pathway. Under the optimized conditions, the pyruvate flux and acetyl-CoA synthesis were low, and much of the acetyl-CoA participated in the tricarboxylic acid cycle.The extracellular acetate flux was 83%, which was 65.13% lower than in the original conditions.

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